Power converters, such as wall plug converters, are used for many applications such as charging mobile phones, laptops, other portable computing devices such as tablets and the like. Power supplies for use in such power converters benefit from increased power densities in order to provide a reduction in size, for example to keep pace with the trend toward increasingly svelte computing devices themselves.
Quasi-square wave refers to a power converter topology that is very efficient at heavy loads. However, at light loads—for example a 30 W converter being operated at 10 W—quasi-square wave converters are less efficient than other converter topologies. Further, various certification standards such as Energy Star may impose certain efficiency requirements on power converters, both at full and reduced load, in order for certification to be granted.